The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
During operative procedures, there is often the need for rapid hemostasis of wounds of parenchymal organs or from venous complexes with a large, actively-bleeding surface area. These wounds are created in over 1.5 Million procedures or traumatic events per year in the United States, including partial nephrectomies, partial hepatectomies, liver transplants, cholecystectomies, liver and spleenic trauma, and radical prostatectomies. The ability to staunch rapid bleeding from such wounds, due to either surgery or external trauma, is often found inadequate with thermal cauterization techniques and can result in high blood loss, termination of the surgery or even death. Consequently, there is a need for better methods of achieving hemostasis in order to allow needed and safer operations. This need is particularly acute in minimally-invasive surgery, a surgical technique that utilizes small laparoscopic ports to access the operative area, rather than large-skin incisions.
Broadly, there are four current methods for obtaining surgical hemostasis: tissue compression using surgical sponges or sutures, use of sutures or clips, application of biological agents and adhesives, and heat cauterization.
Tissue compression hemostasis describes a process whereby pressure is applied to the bleeding surface using a variety of substances, most commonly in the surgical operating theater using cotton gauze. The pressure causes the blood vessels supply the area to collapse and, thereby, stop bleeding temporarily. This technique is most commonly used to obtain temporarily hemostasis prior to attempting permanent hemostasis with another method. Permanent hemostasis can be obtained with compression, however, only if sufficient time is allowed for the patient's natural hemostatic mechanisms to form an adequate clot, and if the patient's natural hemostatic mechanisms are functional. This process is too time-consuming for practical use in the operating room, and clot hemostasis may be less durable than that provided by cautery. Furthermore, release of the clot into the circulation can cause problems in remote areas, such as the brain, heart and lungs.
Biochemical agents can speed the patient's own coagulation cascade and, when applied to the wound, result in more rapid hemostasis. On large, actively-bleeding wounds, these agents are rapidly washed away; attempts at preventing this overlying material have met with mixed success. Tissue adhesives come out, which may be a recapitulation of the clotting cascade or may be completely synthetic and can form an adherent, impervious layer over the wound, but only if they are not dispensed by bleeding and can form a bond with the tissue. Therefore, while promising, biological agents and adhesives have not yet reached the efficacy required for large, actively-bleeding wounds of parenchymal organs or from venous complexes.
Heat cauterization is the oldest and most commonly used hemostatic technique for these wounds. Heat is applied to the wound surface, causing protein coagulation, which plugs the bleeding points and stops the bleeding. Currently, heat cautering operative procedures are almost exclusively achieved via diathermy. For diathermy, the patient is electrically grounded to an AC power source. The grounding is achieved over a very large surface area, distant from the area of operation. A surgical device that completes the circuit is applied to the wound. The complete electrical circuit results in current flow through the tissue between the device and the ground. The current results in electrical resistance heating according to the electrical formula R=V/I, with I being the current density, which is inversely proportional to the cross-sectional area available to the current. The resistance heating coagulates proteins on the wound surface, causing hemostasis. The inverse relationship of current density and cross-sectional area limits the area that can be effectively addressed.
The most common variations of diathermy are electrical cautery, bi-polar cautery and argon beam coagulation. Amongst all methods, argon beam coagulation would be the most direct competitor to this technology. Argon beam coagulation employs a charged device that sprays a stream of argon gas onto the wound. The circuit is completed as the gas provides a guide for an electrical arch to form between the device and the wound area in contact with the gas cloud. There is no compression with this device, but the stream of argon gas is effective as “blowing” blood off the surface of the wound, thereby obviating the dispersion of energy by blood that renders standard electrical cautery ineffective in the operative setting when used to address a more rapidly bleeding wound. There also is no risk of disrupting the coagulum when the device is withdrawn. There is, however, current flow through the patient between the instrument tip and the ground, with the previously-mentioned side effects, as well as a risk of gas embolism. Additionally, the argon gas flow is insufficient to remove the blood from more briskly bleeding wounds. Finally, the area that can be addressed at a given instant with argon beam coagulation is relatively small.
All of the hemostasis methods listed above have advantages and disadvantages, but none sufficiently addresses the challenges associated with large, briskly-bleeding, parenchymal or venous-complex wounds, particularly when they occur during minimally invasive (laparoscopic) operative procedures. Notwithstanding the great effort to make all surgery as minimally-invasive as possible, difficulties with these wounds hamper not only current surgical care, but also the development of new minimally-invasive procedures. The present technology addresses the needs described above to temporarily staunch blood flow and coagulate blood vessels by providing thermal energy in the form of electrical resistance at a temperature optimized for tissue cautery to permanently coagulate bleeding tissue. Such a device can more effectively stop hemorrhaging from parenchymal organs or venous complexes than the prior art, and can be adapted to a minimally-invasive surgery environment.